There is so far known a fuel cell for generating electricity utilizing a fuel gas. The fuel cell is usually made up of a large number of cells. For further improving performance of the fuel cell, there is a demand raised for reducing fluctuations in an electromotive force and a voltage from one cell to another.
In producing a groove-shaped gas path in a separator of the fuel cell for industrial application, there are so far known a method for cutting a metal plate, which is to be a separator, using a suitable cutting tool, to form a groove-shaped gas path, a method for press-working a metal plate, which is to be a separator, to form a groove-shaped passage or duct, and a method for etching (or electroless chemical etching) a metal plate, which is to be a separator of chemically excavating a groove-shaped gas path. The method of producing the gas path by etching (that is, presumed as electroless chemical etching) is disclosed in JP Patent Kokai JP-A-4-267062.